Just wondering what aircraft Airbus and Boeing designed their A350/787 to replace? My understanding of it at the moment is this:

Boeing 787-3 = Boeing 757/Boeing 767-200ER
Boeing 787-8 = Boeing 767-300ER/Airbus A330
Boeing 787-9 = Boeing 767-400ER
Boeing 787-10 = Boeing 777-200ER/Airbus A340-300

Airbus A350-700 = Boeing 767-200ER
Airbus A350-800 = Boeing 767-300ER/Airbus A330
Airbus A350-900 = Boeing 777-200ER/Airbus A340-300
Airbus A350-900R = Boeing 777-200LR/Airbus A340-500
Airbus A350-1000 = Boeing 777-300ER/Airbus A340-600

Also, will the A350 design be refined anymore? I know they’ve just confirmed a composite fuselage, A380 nose, and reduced thrust, but none of those has a great impact on appearance, will those ugly wingtips be improved at all? Also, will the ‘XWB’ bit be dropped from the names?

I think that is a valid list.
The A350 is still some time before design freeze. By now the data for payload and range, as well as overall performance and dimensions can be considered confirmed. When it comes to materials, I think detailed decisions will come the next year or so. Airbus does not need to outlay exactly what they do from composite and what not. I actually think they will wait at least until the B787 is certified.

The A350 pleases airlines that never operated something like a B767, for example Lufthansa. Problem for Airbus is that the small family members (traditionally the less efficient) have to compete against the traditionally more efficient stretched versions of the B787. There is no A350-700. The A350-900 will be the basic version and the A350-800 its shrink.